全文获取类型
收费全文 | 3230篇 |
免费 | 341篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 43篇 |
化学工业 | 845篇 |
金属工艺 | 136篇 |
机械仪表 | 98篇 |
建筑科学 | 78篇 |
矿业工程 | 19篇 |
能源动力 | 159篇 |
轻工业 | 717篇 |
水利工程 | 15篇 |
石油天然气 | 10篇 |
无线电 | 158篇 |
一般工业技术 | 655篇 |
冶金工业 | 84篇 |
原子能技术 | 8篇 |
自动化技术 | 549篇 |
出版年
2023年 | 31篇 |
2022年 | 29篇 |
2021年 | 136篇 |
2020年 | 118篇 |
2019年 | 142篇 |
2018年 | 218篇 |
2017年 | 204篇 |
2016年 | 239篇 |
2015年 | 192篇 |
2014年 | 250篇 |
2013年 | 417篇 |
2012年 | 229篇 |
2011年 | 163篇 |
2010年 | 157篇 |
2009年 | 182篇 |
2008年 | 132篇 |
2007年 | 107篇 |
2006年 | 67篇 |
2005年 | 38篇 |
2004年 | 43篇 |
2003年 | 48篇 |
2002年 | 36篇 |
2001年 | 14篇 |
2000年 | 25篇 |
1999年 | 14篇 |
1998年 | 20篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 16篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 18篇 |
1984年 | 27篇 |
1983年 | 31篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 8篇 |
排序方式: 共有3574条查询结果,搜索用时 609 毫秒
121.
T. Miruszewski B. Trawiński M. Gałka J. Morzy B. Bochentyn J. Karczewski P. Gdaniec M. Gazda B. Kusz 《Materials Science-Poland》2014,32(3):331-340
In order to find a relationship between structural and electrical properties, niobium and yttrium doped SrTiO3 ceramics were prepared via solid-state reaction. The samples were sintered in hydrogen and air conditions. The samples were also fabricated with a pore-former to obtain highly porous specimens. The electrical properties of Nb-doped SrTiO3 samples and yttrium and niobium co-doped SrTiO3 were compared. The comparable electrical properties were observed and discussed according to previous literature reports. It was noticed that the synthesis in a reducing hydrogen atmosphere can increase the solubility of dopants. Moreover, the samples sintered in air presented lower conductivity level and worse structural properties than the samples sintered in hydrogen. The explanation of obtained results was also suggested and discussed. 相似文献
122.
123.
Microbial polyhydroxyalkanoates (PHAs) have been a subject of significant research interest in the past few decades. The recent development of novel functionalized PHAs has opened up new possibilities to combine the good biocompatibility of PHA‐based drug delivery systems to, for example, improve drug loading and release properties, targeting or imaging functionalities. This mini‐review presents some recent scientific developments in the preparation of functionalized PHAs, PHA–drug and PHA–protein conjugates, multifunctional PHA nanoparticles and micelles as well as biosynthetic PHA particles for drug delivery. These developments in combination with the generally excellent biocompatibility of PHA materials are expected to further expand the interest in PHA materials for drug delivery and other therapeutic applications. © 2016 Society of Chemical Industry 相似文献
124.
Ewa Watorek Tomasz Golebiowski Mariusz Kusztal Krzysztof Letachowicz Waldemar Letachowicz Hanna Augustyniak Bartosik Jerzy Garcarek Katarzyna Madziarska Wacław Weyde Marian Klinger 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(1):113-117
Elderly patients, defined as octogenarians and nonagenarians, are an increasing population entering renal replacement therapy. Advanced age appears as an exclusive factor negatively influencing dialysis practice. Elderly patients are referred late for the initiation of hemodialysis and more likely are offered catheters rather than arteriovenous fistulae (AVF), which increase mortality and negatively affect quality of life. We present our approach to the creation of vascular access for hemodialysis in this demanding population. In 2006–2012, 39 patients aged 85.9 ± 2.05 with end‐stage renal disease, mainly resulting from ischemic nephropathy, were admitted to the Department of Nephrology to establish permanent vascular access for hemodialysis: preferably AVF. Temporary dialysis catheters were implanted in uremic emergency to bridge the time to fistula creation/maturation. AVF was attempted in 87.2% of the patients. Primary AVF function was achieved in 54% of the patients. Cumulative proportional survival of AVF at months 12 and 24 was 81.5%. Ninety‐four percent of AVF were localized on the forearm: 74% in the distal and 20% in the proximal part. Mean duration of hemodialysis therapy was 20.80 ± 19.45 months. The mean time of AVF use was 15.9 ± 20.2 months. Until present, 38% have been dialyzed using AVF for 31.0 ± 18.8 months. Five patients died with functioning fistula. Eight patients initiated hemodialysis therapy with fistula. During further observation, the use of AVF increased to 62%. Elderly patients should not be denied creation of AVF as a rule. The outcome of AVF benefits more from acknowledging individual vascular conditions rather than age of the patient. 相似文献
125.
A sequence S is nonrepetitive if no two adjacent blocks of S are the same. In 1906 Thue proved that there exist arbitrarily long nonrepetitive sequences over 3 symbols. We consider the online variant of this result in which a nonrepetitive sequence is constructed during a play between two players: Bob is choosing a position in a sequence and Alice is inserting a symbol on that position taken from a fixed set A. The goal of Bob is to force Alice to create a repetition, and if he succeeds, then the game stops. The goal of Alice is naturally to avoid that and thereby to construct a nonrepetitive sequence of any given length.We prove that Alice has a strategy to play arbitrarily long provided the size of the set A is at least 12. This is the online version of the theorem of Thue. The proof is based on nonrepetitive colorings of outerplanar graphs. On the other hand, one can prove that even over 4 symbols Alice has no chance to play for too long. The minimum size of the set of symbols needed for the online version of Thue?s theorem remains unknown. 相似文献
126.
Mikołaj Bojańczyk 《Theory of Computing Systems》2013,53(2):194-222
We develop an algebraic theory for languages of data words. We prove that, under certain conditions, a language of data words is definable in first-order logic if and only if its syntactic monoid is aperiodic. 相似文献
127.
Paweł Piszcz Magdalena Woźniak Monika Asztemborska Bronisław K. Głód 《Food Analytical Methods》2014,7(7):1474-1480
The present investigation reports on the application of a new antioxidant activity assay for the examination of flavonoids. It has been shown that the high-performance liquid chromatography with electrochemical detection (HPLC–ED) measurements allow to obtain additional information about the antioxidative properties of pure compounds by measuring their half-wave potential, the chromatographic peak height, and the product of the peak height and exponent of potential. In comparison to the classical electrochemical measurements, the HPLC–ED is characterized by a much smaller detection limit. The results were compared with the standard photometric measurement based on 1,1-diphenyl-2-picrylhydrazyl radicals. The possible antioxidant activity forecasting is also discussed. 相似文献
128.
Lipp Natalia Dużmańska-Misiarczyk Natalia Strojny Agnieszka Strojny Paweł 《Virtual Reality》2021,25(2):279-292
Virtual Reality - Virtual reality can be used for educational purposes, particularly in demanding professions such as firefighting. Such virtual training may be useful for preparing trainees for... 相似文献
129.
Maj Justyna Węglewski Witold Bochenek Kamil Rogal Łukasz Woźniacka Stefania Basista Michał 《Metallurgical and Materials Transactions A》2021,52(11):4727-4736
Squeeze casting and powder metallurgy techniques were employed to fabricate AlSi12/Al2O3 composites, which are lightweight structural materials with potential applications in the automotive industry. The impact of the processing route on the material properties was studied. Comparative analyses were conducted for the Vickers hardness, flexural strength, fracture toughness, thermal conductivity, thermal residual stresses, and frictional wear. Our results show that the squeeze cast composite exhibits superior properties to those obtained using powder metallurgy.
相似文献130.
Anna Maria Białostocka Urszula Klekotka Beata Kalska-Szostko 《Chemical Engineering Communications》2019,206(6):804-814
In this article, characterization of FeNi layers deposited on a Cu plate for variable magnetic field arrangement is shown. Layers were prepared using a simple electrodeposition process, from an aqueous solution of Fe2+ and Ni2+ sulfate salts containing boric acid, an iron activator. By application of variation of current values, times, and external magnetic field orientations, the resultant film quality was examined and the efficiency of the embedded elements was investigated. The studies show differences in the coating morphology and relative composition of ferromagnetic metals (Ni, Fe) electrodeposited on a not ferromagnetic (paramagnetic) metal (Cu). The obtained layers were investigated by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy. 相似文献